T.38

T.38 is an ITU recommendation for allowing transmission of fax over IP networks in real time.

History

The T.38 fax relay standard was devised in 1998 as a way to permit faxes to be transported across IP networks between existing Group 3 (G3) fax terminals. T.4 and related fax standards were published by the ITU in 1980, before the rise of the internet. In the late 1990s, VoIP, or Voice over IP, began to gain ground as an alternative to the conventional Public Switched Telephone Network. However, because most VoIP systems are optimized (through their use of aggressive lossy bandwidth-saving compression) for voice rather than data calls, conventional fax machines worked poorly or not at all on them due to the network impairments such as delay, jitter, packet loss, and so on. Thus, some way of transmitting fax over IP was needed.

Overview

In practical scenarios, a T.38 fax call has at least part of the call being carried over PSTN, although this is not required by the T.38 definition, and two T.38 devices can send faxes to each other. This particular type of device is called Internet-Aware Fax device, or IAF, and it is capable of initiating or completing a fax call towards the IP network.

T38

T38 or T-38 may refer to:

T-38 tank

The T-38 amphibious scout tank was a Soviet amphibious light tank that saw service in World War II.

History

Designed in 1934–36 by N. Astrov's bureau at Factory No. 37 in Moscow, the T-38 was a development of the earlier T-37, based in turn on the French AMR 33 light reconnaissance tank. The tank was powered by a standard GAZ (Ford) engine and was cheap to produce. Buoyancy was achieved by the large-volume hull and large fenders. In water, the vehicle was propelled by a small three-bladed propeller mounted at the rear.

The tanks were intended for use for reconnaissance and infantry support. As a scout tank the T-38 had the advantages of very low silhouette and good mobility through its ability to swim. The T-38 was also intended to be air-portable; during the Kiev maneuvers in 1936, the tanks were transported by Tupolev TB-3 bombers, mounted under the fuselage. Infantry battalions were each issued 38 T-38s, with 50 being designated for each airborne armored battalions. However, the thin armor and single machinegun armament made the tank of only limited use in combat while the lack of radios in most T-38s was a serious limitation in a reconnaissance vehicle. The T-38's limitations were recognized, and it would have been replaced by the T-40, but the outbreak of the Second World War meant that only a few T-40s were produced.